A statistical polishing pad model for chemical-mechanical polishing

Chemical mechanical polishing (CMP) has emerged as a critical technology for advanced integrated circuit fabrication. This paper presents for the first time a physical CMP model that includes the effects of polishing pad roughness and dynamic interaction between pad and wafer. Two new feature-scale polishing mechanisms based on asperity theory are proposed and investigated experimentally. a statistical asperity model is first introduced and applied to characterize surface roughness of polishing pads. The data is then used to calculate pad-wafer contact properties and predict feature-scale polishing rates. CMP experiments suggest that the time-dependent deformation of polishing pads and asperity-device interaction both affect planarization of device features.<>